The invention relates to a water-cooled exhaust gas re-circulation device disposed at an exhaust gas re-circulation passage of an internal combustion engine such as engines.
FIG. 1 illustrates a schematic representation of the whole of a conventional cooling water re-circulation passage arranged at the internal combustion engine. FIG. 2 is a front view of a water-cooled exhaust gas re-circulation device arranged at the conventional cooling water re-circulation of FIG. 1. FIG. 3 is a cross sectional view taken along lines IIIxe2x80x94III of FIG. 2. FIG. 4 is a cross sectional view of a hole formed at a part of the cooling water re-circulation passage within the water-cooled exhaust gas re-circulation device during a die casting.
In these drawings, a reference numeral 1 denotes a cooling water re-circulation passage, and a reference numeral 2 denotes a water-cooled exhaust gas re-circulation device arranged at the cooling water re-circulation passage 1. A reference numeral 3 denotes a drain bolt independent of other components arranged at the cooling water re-circulation passage 1 close to a cylinder block and constituting a hole communicating the cooling water re-circulation passage 1 and outside air. A reference numeral 4 denotes a radiator preventing the cooling water re-circulated in the cooling water re-circulation passage 1 from increasing the temperature. A reference numeral 5 denotes a drain cock acting as an outlet of the cooling water when the cooling water is changed to new one. A reference numeral 6 denotes a radiator cap controlling an internal pressure of the cooling water re-circulation passage 1. The radiator cap 6 constitutes an air hole, which is close to the radiator when the cooling water is changed to new one, and an inlet of the cooling water when the cooling water is supplied to the cooling water re-circulation passage 1. A reference numeral 7 denotes a cylinder block constituting an external engine. A reference numeral 8 denotes a water pump arranged in the cooling water re-circulation passage 1 and supplying the cooling water to the cylinder block 7 of the engine in order to re-circulate it in the cooling water re-circulation passage 1.
The water-cooled exhaust gas re-circulation device 2 includes a valve housing 10 including an exhaust gas re-circulation valve (not shown) and a motor main body 11 including a motor driving the exhaust gas re-circulation valve as shown in FIG. 2 and FIG. 3. The motor main body 11 is affixed to the valve housing 10 with screws 12. A reference numeral 13 denotes a terminal supplying electric power to the motor (not shown) arranged in the motor main body 11. Reference numerals 14 and 15 denote inlet and outlet of an exhaust gas re-circulation passage, which is opened and closed due to the exhaust gas re-circulation valve. A reference numeral 16 denotes a nipple guiding the cooling water from the cooling water re-circulation passage 1, which is close to the engine, to the cooling water re-circulation passage 1 within the water-cooled exhaust gas re-circulation device 2. When the cooling water re-circulation passage 1 in the water-cooled is manufactured due to the die casting, it is necessary to form a hole 17 arranged at a part of the passage 1 as shown in FIG. 4. With a conventional constitution, the hole 17 was filled with a plug 18 as shown in FIG. 3.
With the cooling water re-circulation passage 1, when the cooling water is changed to new one, the drain cock 5 arranged at a lower section of the radiator 4 is used as a discharge port of the cooling water and the radiator cap 6 mounted on an upper section of the radiator 4 is used as the air hole.
First, as shown in FIG. 1, to discharge the cooling water to change it to new one, the temperature of the cooling water is adequately reduced after stopping the engine. With the state, while adjusting an internal pressure of the cooling water re-circulation passage 1 due to open/close of the radiator cap 6, the radiator cap 6 is opened to introduce air to the cooling water re-circulation passage 1. The drain cock 5 is then opened to discharge the cooling water. The drain bolt 3 acting as the air hole close to the engine is opened and the cooling water close to the engine is conveyed toward the radiator to discharge it to outside through the drain cock 5.
Next, to supply the cooling water to the passage 1, the required amount of the cooling water is supplied to the passage 1 through the radiator cap 6 after the drain cock 5 is closed. When the cooling water is supplied, the drain bolt 3 acts as an air hole discharging smoothly air in the cooling water re-circulation passage 1 to outside.
With the conventional structure, it is possible to smoothly discharge the cooling water, which is close to the radiator 4, of the cooling water re-circulation passage 1 due to the radiator cap 6. It is further possible to smoothly discharge the cooling water, which is close to the engine having a complex structure, due to the drain bolt 3 arranged at a position higher than the engine side.
However, since the drain bolt 3 is arranged independently at the conventional cooling water re-circulation passage 1, the conventional water-cooled exhaust gas re-circulation device has a complex layout to produce a redundant space and parts.
The invention was made to solve the foregoing problems. An object of the invention is to provide a water-cooled exhaust gas re-circulation device allowing simplifying the layout of the cooling water re-circulation passage and reducing costs due to reducing a component count and saving a space.
A water-cooled exhaust gas re-circulation device according to the invention is characterized in that a hole open/close mechanism allowing communication with outside air is arranged at a cooling water re-circulation passage cooling an exhaust gas re-circulation valve. In this way, since the cooling water re-circulation passage is integrated with the hole-open/close mechanism, it is possible to remove the drain bolt arranged independently of the exhaust gas re-circulation valve. It is possible to allow saving space, simplifying the structure and reducing a component count.
With the above arrangement, the water-cooled exhaust gas re-circulation device is characterized in that the hole-open/close mechanism is a drain bolt. In this way, even if an interference substance is close to the drain bolt, it is possible to ensure an air hole with respect to the cooling water re-circulation passage without removing the drain bolt.
With the above arrangement, the water-cooled exhaust gas re-circulation device is characterized in that the hole-open/close mechanism is arranged at a stopper stopping up a hole formed during manufacturing the cooling water re-circulation passage. In this way, it is not necessary to form an exclusive hole at the cooling water re-circulation passage in order to install the hole-open/close mechanism. It is possible to allow reducing costs and saving a space as compared with a case of forming the exclusive hole.